# Re: Nail Slip

• To: seaint(--nospam--at)seaint.org
• Subject: Re: Nail Slip
• Date: Fri, 18 Aug 2000 19:47:31 -0700
```Bill, I will send you the derivation of the shear wall deflection formula. Yes,
there are terms within the constant that cancel out in the formula for wall
deflection due to nail slip. The constant is 1/ft, h is ft, and e-n is in
inches.

We have had several test projects where calculated shear wall deflection is
compared to measured deflection recorded in the tests (at design shear load, and
up to 1.4x design shear load). There is good agreement in these values. APA
Report 158 summarizes these observations in cyclic shear wall tests conducted at
UCI.

Yes, hold-down slip can be a significant factor in shear wall deflection,
especially for narrow shear walls (aspect ratio greater than 1.0). We think that
the lag-screw or nailed type hold-downs are best because they limit
slip/deformation. In my opinion, the single-shear bolted-type hold-down should
be used in conjunction with a dadoed shear plate connector, to limit bolt
deformation and potential splitting of the end studs/post.

John Rose/APA

Bill Allen wrote:

> John-
>
> Maybe when solving this equation by hand, the problem with the units is not
> apparent, but it is when using something like Mathcad. This is why I had to
> include a "12" in the denominator in the first and third terms in my
> example.
>
> More importantly, I invite attention to the results of the sample I posted
> on the web. Once again, see:
>
> http://www.allendesigns.com/sw/shearwalldeflections.htm
>
> If you notice, this is a fairly "normal" (i.e., moderately loaded) shear
> wall. Even though the aspect ratio meets Code (2:1), the deflection is
> (slightly) excessive (0.0266h vs. an allowable of 0.025h). This is mostly
> due to the use of a HD instead of a PHD or some other device which minimizes
> hold down deflections.
>
> Imagine a highly loaded shear wall.
>
> Thanks,
>
> Bill Allen, S.E. (CA #2607)
> ALLEN DESIGNS
> Consulting Structural Engineers
> Laguna Niguel, CA
> http://www.AllenDesigns.com
> V (949) 365-5696
> F (949) 249-2297
>
> ||-----Original Message-----
> ||Sent: Wednesday, August 16, 2000 11:16 PM
> ||To: seaint(--nospam--at)seaint.org
> ||Subject: Re: Nail Slip
> ||
> ||
> ||Bill, it is dimensionally consistent. There are factors
> ||within the constants for
> ||each term that account for the apparent inconsistencies. Same
> ||applies to
> ||diaphragm deflection equation.
> ||John Rose/APA
> ||
> ||Bill Allen wrote:
> ||
> ||> Nels-
> ||>
> ||> As Dennis Wish once pointed out, this equation (along with
> ||others) is not
> ||> dimensionally consistent. I worked an example in Mathcad
> ||and converted it to
> ||> html. You can view this example at:
> ||>
> ||> http://www.allendesigns.com/sw/shearwalldeflections.htm
> ||>
> ||> I hope this helps in making this equation clearer.
> ||>
> ||> Regards,
> ||>
> ||> Bill Allen, S.E. (CA #2607)
> ||> ALLEN DESIGNS
> ||> Consulting Structural Engineers
> ||> Laguna Niguel, CA
> ||> http://www.AllenDesigns.com
> ||> V (949) 365-5696
> ||> F (949) 249-2297
> ||>
> ||> ||-----Original Message-----
> ||> ||From: Nels Roselund [mailto:n.roselund(--nospam--at)worldnet.att.net]
> ||> ||Sent: Tuesday, August 15, 2000 6:08 PM
> ||> ||To: seaint(--nospam--at)seaint.org
> ||> ||Subject: Re: Nail Slip
> ||> ||
> ||> ||
> ||> ||Mike,
> ||> ||
> ||> ||Thanks for pointing me to the answer.
> ||> ||
> ||> ||Your explanation [in the Archives], that the implied units of
> ||> ||the constant
> ||> ||in the nail-slip term of the equation is 1/ft, seems to make
> ||> ||sense.  It
> ||> ||gives the nail slip term a value of 1/12  of the result I got
> ||> ||by making the
> ||> ||Table value of en unit-less.  It also gives a result that
> ||makes the
> ||> ||contribution of nail-slip to the total deflection small
> ||> ||rather than the
> ||> ||major component of shear wall deflection.
> ||> ||
> ||> ||If the implied units of the constant were to be taken as
> ||> ||1/in, the result
> ||> ||would be the same as making en unit-less.
> ||> ||
> ||> ||Is your use of an implied value of 1/ft rather than 1/in based on
> ||> ||documentation, or on what you know of the derivation of
> ||the deflection
> ||> ||equation?  Or is your explanation based on what you, too,
> ||> ||found to give the
> ||> ||most sensible results?  I'd like to know that there is
> ||> ||documentation and how
> ||> ||to find it.  I don't like to have to  use magic formulas.
> ||> ||
> ||> ||Nels Roselund
> ||> ||Structural Engineer
> ||> ||
> ||> ||
> ||> ||-----Original Message-----
> ||> ||From: Mike Valley <mtv(--nospam--at)skilling.com>
> ||> ||To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
> ||> ||Cc: n.roselund(--nospam--at)worldnet.att.net <n.roselund(--nospam--at)worldnet.att.net>
> ||> ||Date: Tuesday, August 15, 2000 3:32 PM
> ||> ||Subject: RE: Nail Slip
> ||> ||
> ||> ||
> ||> ||>This was discussed on the list in July of 1999.  I
> ||posted on 7/8 and
> ||> ||>7/15.  The archives contain the info.
> ||> ||>
> ||> ||>- - - - - - - - - - - - - - - - - - - - - - - - - - - -
> ||- - - - - - -
> ||> ||>Michael Valley, P.E., S.E.                   E-mail:
> ||mtv(--nospam--at)skilling.com
> ||> ||>Skilling Ward Magnusson Barkshire Inc.
> ||Tel:(206)292-1200
> ||> ||>1301 Fifth Ave, #3200,  Seattle  WA 98101-2699      Fax:
> ||       -1201
>
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